The present invention is generally related to an improvement of synthetic resin extruding means having an end provided with a mouth for feeding a raw resin material into, and the other end provided with an extruding mouth for extruding a molten quantity of resin material through a cylindrical heater means wherein a screw shaft is rotatably inserted so as to feed the material to the extruding mouth, and more in particular to an improved construction of extruding means having a screw shaft portion provided with a kneading means for a raw material resin material, which means is able not only to carry out a more efficient kneading operation but also to shift the same into the conventional kneading operation.